Aims: To document the clinical, light microscopic, immunohistochemical and ultrastructural features of four cases of extra-orbital giant cell angiofibromas.
Methods and results: Sections of formalin-fixed paraffin-embedded specimens were studied by haematoxylin and eosin, reticulin and immunohistochemical stains. Electron microscopy was carried out in two cases on tissue fixed in formalin. The age of the patients ranged from 30 to 41 years. Two patients presented with a soft tissue swelling in the left groin, one patient had a left axillary soft tissue lump and one patient presented with a parotid lump. All lesions were well circumscribed and contained variably cellular and vascularized tissue composed of round to spindle cells with a patternless arrangement, scattered multinucleate giant cells and pseudovascular spaces conforming to the description of giant cell angiofibroma. Mononuclear and multinucleate tumour cells were both positive for vimentin and CD34; one tumour exhibited focal S100 protein and GFAP positivity. Both of the tumours examined by electron microscopy showed fibroblastic features, but in addition one contained cells having Schwannian features. All four patients were well without recurrent disease on follow-up (average 25 months).
Conclusion: Giant cell angiofibroma shares many features with solitary fibrous tumour and giant cell fibroblastoma and shows a wider distribution than initially recognized. Rarely, Schwannian differentiation may be observed in these tumours.